A novel theory of effective mechanical properties of closed-cell foam materials

2013 ◽  
Vol 26 (6) ◽  
pp. 559-569 ◽  
Author(s):  
Yuli Ma ◽  
Xianyue Su ◽  
R. Pyrz ◽  
J. Ch. Rauhe
Keyword(s):  
Mechanical Properties ◽  
Closed Cell ◽  
Novel Theory ◽  
Cell Foam ◽  
Effective Mechanical Properties

scholarly journals The Mechanical Properties and the Influence of Parameters for Metallic Closed-Cell Foam Subjected to High-Strain Rates

2015 ◽  
Vol 1119 ◽  
pp. 799-806
Author(s):  
Charles E. Lord ◽  
Zhen Huang
Keyword(s):  
Mechanical Properties ◽  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
Metallic Foam ◽  
Strain Rates ◽  
Hopkinson Pressure Bar ◽  
High Strain Rates ◽  
Closed Cell ◽  
Pressure Bar ◽  
Cell Foam

As the trend for lighter more efficient structures continues, the requirement for alternative materials follows. One material that has gained attention more recently is porous metallic foam. One drawback to these materials is that there is limited pedigree and understanding of their performance. As with all materials, the use of metallic foam for structures requires knowledge of its mechanical properties; including at high-strain rates. The focus of this paper is to determine the compressive mechanical properties and the influencing parameters for AISI 4340 steel closed-cell foam under high-strain rates (776s-1 to 3007s-1). ANSYS commercial finite element code is used to simulate a closed-cell sample under a split Hopkinson pressure bar test. In this paper the pores are considered to be spherical in shape for simplification while various parameters such as the pore size, the number of pores, the distribution of pores, and the strain rate are varied. Each of these parameters gives this material a unique response which is presented in this paper.

scholarly journals How does vacuum forming affect Pelite mechanical properties?

1994 ◽  
Vol 18 (1) ◽  
pp. 43-48 ◽  
Author(s):  
J. E. Sanders ◽  
C. H. Daly
Keyword(s):  
Mechanical Properties ◽  
Strain Curve ◽  
Shear Loading ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Closed Cell ◽  
Vacuum Forming ◽  
Interface Mechanics ◽  
Computer Aided ◽  
Cell Foam

Pelite® is a polyethylene closed cell foam commonly used as an interface material in prosthetics. Both normal and vacuum-formed Pelite were tested under compression and under shear loading. For shear testing, the results were not significantly different for normal and vacuum-formed Pelite. For normal Pelite, the slope of the stress-strain curve was 1.17MPa (±0.14) while for vacuum-formed Pelite it was 1.24MPa (±0.22). Compressive results, however, were significantly different. Below 80kPa of applied compression, the slope of the stress-strain curve for normal Pelite was 0.99MPa (±0.11) while for vacuum formed Pelite it was 0.72MPa (±0.12). Between 80kPa and 200kPa of applied compression, the slope of the stress-strain curve for normal Pelite was 0.45MPa (±0.03) while for vacuum formed Pelite it was 0.55MPa (±0.05). Reasons for the differences and their significance to interface mechanics and computer-aided prosthesis design are discussed.

scholarly journals Static Mechanical Properties of Expanded Polypropylene Crushable Foam

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 249
Author(s):  
Przemysław Rumianek ◽  
Tomasz Dobosz ◽  
Radosław Nowak ◽  
Piotr Dziewit ◽  
Andrzej Aromiński
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Strain Rate ◽  
Energy Absorption ◽  
Experimental Tests ◽  
Absorption Capacity ◽  
Strain Rates ◽  
Foam Density ◽  
Energy Absorption Capacity ◽  
Closed Cell

Closed-cell expanded polypropylene (EPP) foam is commonly used in car bumpers for the purpose of absorbing energy impacts. Characterization of the foam’s mechanical properties at varying strain rates is essential for selecting the proper material used as a protective structure in dynamic loading application. The aim of the study was to investigate the influence of loading strain rate, material density, and microstructure on compressive strength and energy absorption capacity for closed-cell polymeric foams. We performed quasi-static compressive strength tests with strain rates in the range of 0.2 to 25 mm/s, using a hydraulically controlled material testing system (MTS) for different foam densities in the range 20 g/dm3 to 220 g/dm3. The above tests were carried out as numerical simulation using ABAQUS software. The verification of the properties was carried out on the basis of experimental tests and simulations performed using the finite element method. The method of modelling the structure of the tested sample has an impact on the stress values. Experimental tests were performed for various loads and at various initial temperatures of the tested sample. We found that increasing both the strain rate of loading and foam density raised the compressive strength and energy absorption capacity. Increasing the ambient and tested sample temperature caused a decrease in compressive strength and energy absorption capacity. For the same foam density, differences in foam microstructures were causing differences in strength and energy absorption capacity when testing at the same loading strain rate. To sum up, tuning the microstructure of foams could be used to acquire desired global materials properties. Precise material description extends the possibility of using EPP foams in various applications.

Microstructure and mechanical properties of ALPORAS closed-cell aluminium foam

2015 ◽  
Vol 107 ◽  
pp. 228-238 ◽  
Author(s):  
Wen-Yea Jang ◽  
Wen-Yen Hsieh ◽  
Ching-Chien Miao ◽  
Yu-Chang Yen
Keyword(s):  
Mechanical Properties ◽  
Aluminium Foam ◽  
Microstructure And Mechanical Properties ◽  
Closed Cell

Temperature dependency of the long-term thermal conductivity of spray polyurethane foam

2021 ◽  
pp. 174425912110454
Author(s):  
Neal Holcroft
Keyword(s):  
Thermal Conductivity ◽  
Polyurethane Foam ◽  
Cellular Structure ◽  
Gas Diffusion ◽  
Temperature Dependent ◽  
Blowing Agent ◽  
Closed Cell ◽  
Wall Assembly ◽  
Cell Foam

The thermal properties of closed-cell foam insulation display a more complex behaviour than other construction materials due to the properties of the blowing agent captured in their cellular structure. Over time, blowing agent diffuses out from and air into the cellular structure resulting in an increase in thermal conductivity, a process that is temperature dependent. Some blowing agents also condense at temperatures within the in-service range of the insulation, resulting in non-linear temperature dependent relationships. Moreover, diffusion of moisture into the cellular structure increases thermal conductivity. Standards exist to quantify the effect of gas diffusion on thermal conductivity, however only at standard laboratory conditions. In this paper a new test procedure is described that includes calculation methods to determine Temperature Dependent Long-Term Thermal Conductivity (LTTC(T)) functions for closed-cell foam insulation using as a test material, a Medium-Density Spray Polyurethane Foam (MDSPF). Tests results are provided to show the validity of the method and to investigate the effects of both conditioning and mean test temperature on change in thermal conductivity. In addition, testing was conducted to produce a moisture dependent thermal conductivity function. The resulting functions were used in hygrothermal simulations to assess the effect of foam aging, in-service temperature and moisture content on the performance of a typical wall assembly incorporating MDSPF located in four Canadian climate zones. Results show that after 1 year, mean thermal conductivity increased 15%–16% and after 5 years 23%–24%, depending on climate zone. Furthermore, the use of the LTTC(T) function to calculate the wall assembly U-value improved accuracy between 3% and 5%.

scholarly journals Study of Physical Properties and Shock Absorption Abilities of Starch Polymer Foam as Cushioning Material for Packaging

2018 ◽  
Vol 225 ◽  
pp. 06010
Author(s):  
N. Amir ◽  
Mohamed Syakir Mohamed Hisham ◽  
Kamal Ariff Zainal Abidin
Keyword(s):  
Average Density ◽  
Curing Process ◽  
Polymer Foam ◽  
Shock Absorption ◽  
Open Cell ◽  
Lack Of Information ◽  
Closed Cell ◽  
Open Cell Foam ◽  
Cell Foam ◽  
Cushioning Material

Lack of information about the formulation and fabrication process of starch polymer foam and lack of study in the shock absorption ability of starch polymer foam were the reasons this research was executed. In this project starch polymer foam was produced to be used as cushioning material for packaging. Starch polymer foam were developed from starch, polyvinyl alcohol (PVA), urea, citric acid, and deionised water. Water amount with drying and curing process were the variables manipulated to produce the best starch polymer foam. It was determined then, that the optimized ratio of starch:PVA:citric acid was 1:1:4. The amount of water used was 10 ml/gram of starch/PVA weight. The suitable foaming mixing was done at a speed of 1500 rpm for 40 minutes. Drying process was done at 70°C for 24 hours, followed by curing process at 100°C for 1 hour to produce closed-cell foam. While for the open-cell foam, the foam was dried and cured at 100ºC for 6 hours. The open-cell and closed-cell foams produced were cut to 6 cm height x 6 cm width x 0.5 cm thick. The average density was calculated and then the foams were subjected to weight drop destructive test. The test was done by placing a foam on top of a piece of mirror, and a weight is dropped onto the foam, with increasing height until the mirror break. Three weights were used with mass of 50 g, 100 g and 200 g. The starch foams were compared to polyurethane and polystyrene foams in terms of the minimum height that can cause the mirror to break. The results showed that starch closed-cell foam absorbed the highest impact energy followed by polystyrene foam, starch open-cell foam and polyurethane foam.

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